

SSCommitted
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Only the second query is getting the right answer. #1 and #3 are getting +1 to the my current age.




Ten Centuries
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The third solution is clearly incorrect  given a datetime value of 01/26/1978.
i.e.
declare @DateOfBirth datetime set @DateOfBirth = '19780126 00:00:00.000'
select @DateOfBirth
select DATEDIFF(yy, @DateOfBirth, GETDATE())
select FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, GETDATE())) / 365.0)
select DATEDIFF(yy, @DateOfBirth, GETDATE())  CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END
Returns:
30  Correct
30  Correct
29  Incorrect
Tommy




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I intuitively choose 2 because 1 and 3 are definitely wrong. 1 doesn't take care of month and day of birth at all and 3 does it in the wrong way. But the are all wrong. It can be easily verified with the script below. Play around with some values at the beginning and end of the month in both dates. I added a fourth solution which I think is correct.
declare @DateOfBirth datetime declare @Today datetime
select @DateOfBirth = '2004/03/01' select @Today = '2008/02/29'
select DATEDIFF(yy, @DateOfBirth, @today) select FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, @Today)) / 365.0) select DATEDIFF(yy, @DateOfBirth, @today)  CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, @Today) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, @Today) THEN 0 ELSE 1 END select DATEDIFF(yy, @DateOfBirth, @today)  CASE WHEN DATEPART(m, @Today) > DATEPART(m, @DateOfBirth) OR (DATEPART(m, @Today) = DATEPART(m, @DateOfBirth) AND DATEPART(d, @Today) >= DATEPART(d, @DateOfBirth)) THEN 0 ELSE 1 END




Ten Centuries
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Of course, I suppose the real point of the question was to draw attention to the fact that (1) was wrong and (2) was inaccurate. But it would have been helpful to have a correct solution in the mix. :)
Derek




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I originally thought the 1 and 0 were switched but actually, the two comparisons should be >=




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I also ran all three queries with my birthdate, and the first and third returned the wrong answer. However, the second one was correct.




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That one works flawlessly.
DECLARE @DateOfBirth VARCHAR(10) SET @DateOfBirth = '19600307'
print YEAR(GETDATE())  YEAR(@DateOfBirth)  CASE WHEN MONTH(GETDATE())*31 + DAY(GETDATE()) >= MONTH(@DateOfBirth)*31 + DAY(@DateOfBirth) THEN 0 ELSE 1 END




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The formula is incorrect. If your birthday has occurred in the calendar year, the formula below returns 1 year less than it should. I know many people that would be happy if the formula was correct, but I am afraid they really are the age that DATEDIFF(yy, DateOfBirth, GETDATE()) gives.
DATEDIFF(yy, DateOfBirth, GETDATE())  CASE WHEN DATEPART(m, DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END
Q
Please take a number. Now serving emergency 1,203,894




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Another point  the question specifies TINYINT, none of the queries return TINYINT. (1) is INT, (2) is DECIMAL, (3) is INT. Not only are the queries inaccurate, but none of them fit the criteria ...




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sorry the 3rd answer is not 100% correct as written
DECLARE @DateOfBirth DATETIME SET @DateOfBirth='08/xx/1975' commented out the day just because
SELECT DATEDIFF(yy, @DateOfBirth, GETDATE()) AS [first], FLOOR(CONVERT(decimal(9, 2), DATEDIFF(d, @DateOfBirth, GETDATE())) / 365.0) AS [second], DATEDIFF(yy, @DateOfBirth, GETDATE())  CASE WHEN DATEPART(m, @DateOfBirth) >= DATEPART(m, GETDATE()) AND DATEPART(d, @DateOfBirth) >= DATEPART(d, GETDATE()) THEN 0 ELSE 1 END AS [third]
the result when it runs first second third 33 32 33
Don't age me before my time, only the second one was correct.



